STELLITE OR KOLSTERISING HARD FACE 1

[GabrieleB]

Anyone can explain me the difference beetwen KOLSTERISING hard face treatment and STELLITE. Which of these treatment has better wear resistance? Which has more hardness? Which is more expensive? Tanks in advance for your help.

 

[ione]

Stellite is a commercial name of a cobalt-chrome alloy available in different grades and with high wear resistance features (Deloro is the proprietary of the trademark).

You can find useful info on this website

http://www.stellite.com/Technical/Research/tabid/259/Default.aspx

Kolsterising is a low temperature diffusion process used to create a high resistance carbon layer (from the surface towards the centre of the material for about 20 – 40 µm). The carbon diffused in the steel lattice increases hardness and produces beneficial effects (fatigue resistance) due to induced compressive stress.

You can find useful info on this website

http://internet.bodycote.org/kolsterising/en/properties.html

 

[MattC1234]

I am quite interested in this myself. Kolterising seemingly increases the hardness and (i assume) the erosion resistance of the Steel and judging by the figures provided on the site, it will have a higher HRc than Stellite.

Reading between the lines i would suggest that kolsterising increases the wear resistance beyond that of hard facing the material with Stellite, whilst also keeping the corrosion resistance of the base metal. No clue on the price though, Stellite, although not cheap i would think was cheaper because it is more widely used. Kolsterising may be expensive simply due to lack of people able to do it.

Anyone else got any experiance with this, rather than just reading from websites?

 

[GabrieleB]

Matt1234 confirm what is my opinion about this surface treatment. I think that Kolsterising have better wear resistance in erosive environment. A Vendor of Control Valves offer me this alternative in place of stellite and is very interesting for me to know if this hard face treatment is applicable for high erosive environment.
Thanks for your answer that confirm my good opinion about this hard face treatment.

 

[ione]

Stellite 6B is one of the best wear resistant material, but the problem is its price. Stainless alloys such as S20161 and S21800, have gained popularity due to their more competitive price coupled with good properties of wear resistance (cavitation erosion and galling) and they can be regarded as good replacements for Stellite in valve and pump applications.

Kolsterised austenitic products also offer a good resistance to galling (adhesive wear), as despite of the increased hardness, the diffused carbon layer keeps a good degree of deformability.
The corrosion resistance of the austenitic matrix is also not affected by the treatment, and this a great achievement if compared to the effect produced by other thermal diffusing treatment, such as nitriding.

 

[micalbrch]

We have experience with both. Stellite is harder and more expensive. But I do not dare to say that it is better in all applications.

 

[MattC1234]

Micalbrch - you say that Stellite is harder, but seemingly thr figures say otherwise, can you elaborate more on this?

Cheers!

 

[GabrieleB]

I know that stellite hardness is up to 55 HRC (about 600 Vickers) or little more. Kolsterised treatment guarantees up to 1000-1200 Vickers. This values seems to indicate higher wear properties with kolsterised hard face treatment. If anyone has a different opinion, I'm pleasure to hear him. Thank for your support.

 

[ione]

Stellite100 (HRC = 63 or Vickers =772 at 20 °C) source Deloro

Stellite98M2 (HRC = 60 or Vickers =697 at 20 °C) source Deloro

Kolsterized austenitic stainless steel (HRC up to 74 approx 1400 Vickers) source Bodycote

 

[ione]

Hardness is a very important parameter, but it is reductive to consider it as the only parameter to be taken into account in order to evaluate how good is a material to face wear issues. It is not unusual to have metal items lined with soft rubber to better withstand impact wear (i.e hydrocyclones). It is important to be focused on the different types of wear, which often simultaneously occur producing combined effects. Kolsterising is a valid solution as it offers a high hardness coupled with a still appreciable deformability and an unaffected corrosion resistance of the stainless steel matrix.

 

[micalbrch]

MattC1234: Have a look at the Stellite Homepage. There are alloys which exceed the hardness of kolsterised parts. But I confess that these alloys are not called Stellite although they are made by Stellite. So, my post was a little bit unclear or not precise enough.

 

[JulianBashore]

GabrieleB: Our company (Bodycote) offers the Kolsterising process to a number of valve manufacturers in Europe, North America, and Asia. Please contact me if you require more information on Kolsterising and other proprietary technologies in our lineup.

Best regards,
Julian

Bodycote plc

http://www.bodycote.com